Embodiments relate to an image sensor and a method of manufacturing an image sensor.
Image sensors may include semiconductor devices which may convert optical images into electrical signals. Image sensors may be classified as charged coupled devices (CCDs) and/or complementary metal oxide semiconductor (CMOS) image sensors (CIS). CMOS image sensors may have structure in which a photodiode region, which may convert optical signals into electrical signals, and a transistor region, which may process electrical signals, may be horizontally disposed. A horizontal type image sensor may include a photodiode region and/or a transistor region horizontally disposed on and/or over a semiconductor substrate, such that there may be a drawback in expanding an optical sensing part, which may reference a fill factor, due to a relatively limited area.
To address drawbacks, attempts of forming a photodiode using amorphous silicon (Si), and/or forming a circuitry on and/or over a silicon (Si) substrate and/or forming a photodiode on and/or over a readout circuitry using a wafer-to-wafer bonding method may be attempted, which may reference a three-dimensional (3D) image sensor. A photodiode may be connected to circuitry through a metal interconnection. However, since a bonding surface between wafers in wafer-to-wafer bonding may be relatively uneven, bonding strength may be reduced. Relatively slight height differences may be generated according to positions on and/or over a surface of a wafer including a circuitry and/or an interconnection as a semiconductor processes may be repeatedly performed. When a wafer including a circuitry and/or an interconnection may be bonded to a wafer including a photodiode, mutual bonding strength may be minimized A peeling phenomenon may result.
Accordingly, there is a need for an image sensor and a method of manufacturing an image sensor which may include a vertical-type image sensing device and/or form a metal layer on and/or over a bonding surface between an image sensing device and an interlayer dielectric, for example to maximize bonding strength.